Deselect row/column on click outside

[danistefanovic]

Right now, when you click a row or column header, it stays highlighted, even after clicking elsewhere (like a cell or background). This feels similar to focus behavior but doesn’t behave like typical focus, which can be confusing.

It would improve usability if clicking anywhere outside the header (e.g. a cell or blank space) would deselect the active row or column. This would make the interaction feel more intuitive and aligned with user expectations.